In only the second veto of his presidency, Bush rejected legislation pushed by Democratic leaders that would require the first U.S. combat troops to be withdrawn from Iraq by Oct. 1 with a goal of a complete pullout six months later.

"This is a prescription for chaos and confusion and we must not impose it on our troops," Bush said in a nationally broadcast statement from the White House. He said the bill would "mandate a rigid and artificial deadline" for troop pullouts, and "it makes no sense to tell the enemy when you plan to start withdrawing."

Democrats made a last-minute plea for Bush to sign the bill, knowing their request would be ignored. "The president has put our troops in the middle of a civil war," said Senate Majority Leader Harry Reid. "Reality on the ground proves what we all know: A change of course is needed."

Sen. Daniel Akaka called the veto a "huge mistake."

Hear more comments by Akaka on Bush's veto of the Iraq war funding bill.

House Speaker Nancy Pelosi said the legislation "respects the wishes of the American people to end the Iraq war."

Lacking the votes to override the president, Democratic leaders quietly considered what might be included or kept out of their next version of the $124 billion spending bill. Bush will meet with congressional leaders — Democrats and Republicans alike — on Wednesday to discuss a new bill.

Bush said Democrats had made a political statement by passing anti-war legislation. "They've sent their message, and now it's time to put politics behind us and support our troops with the funds," the president said.

He said the need to act is urgent because without a war-funding bill, the armed forces will have to consider cutting back on buying or repairing equipment.

"Our troops and their families deserve better, and their elected leaders can do better," Bush said.